51.(when)and (by whom)the islands of the west Indies were first settled is a matter (of debating)(among)archaeologists.
52.(Cliff's and Al's)car (broke down)again,but (luckily)they knew (how to fix)it.
53.(from the top )of the tower,Jacob was able (to clearly and easily see)the (whole )city (stretching)out below him.
54.Joan (decided)that she did not like the (girl eating)an ice-cream cone on the bus after (she)(yelled)at her little brother.
Key：
1-10BBBBD-ADCAB
11-20CCBCC-BABBD
21-30BBCCB-BACAA
31-40CCBAA-DCBAB
41-50BCADC-CAADD
51-54CABC
